Cutter relief mechanism for milling machines



July 20, 1948. c. 1.. HOLMSTROM 2,

cuwmn RELIEF MECHANISM ron MILLING umcnmns Filed Aug. 9, 1944 2 Sheets-Sheet 1 I l I I l -l---' IN VEN TOR.

CUTTER RELIEF uscmmsm FOR MILLING mcamns Filed Aug. 9, 1944 July 20, 1948. c. 1.. HOLMSTROM 2 Sheets-Sheet 2 INVENTOR. CARL LHOLMSTROM Patented July 20, 1948 UNITE D STATES PATENT OFFICE.

CUTTER RELIEF MECHANISM, FOR MILLING MACHINES Carl- Lelan'd-Holmstrom, Rockford, 111 assignor to Sundstrand; Machine Tool 00., Rockford, 111., a corporation of Illinois ApplicationAugust 9, 1944, Serial No. 548,686

ing machine and stop means for limiting itsmovement in either direction, together with a member actuated by the movement of the quill and arranged for engagement with the stop means, the connection between the quill and said member being such that all backlash intheconnection is taken up before the member engages a stop.

It is also an object of the invention to provide an adjustable quill for a milling machine, to-

gether with stops limiting, its movementin either direction, and means for holdingthe quill forcibly at either limit while th millingtool completes a portion of its cycle to which thatpositionof the quill corresponds.

More specifically, it is arr-object of the invention to provide a quill mounted-for axial adijustment and having. a rack with which a driving pinion meshes for effecting such-adi-ustnierittogether with a secondpinion meshing with the rack, a shouldered rodslidable between stops and driven by the second pinion wherelo'y all-back lash between the rodv and the quill: is taken upbefore a shoulder of the rodv engages: one of the stops to limitzthe movement: ofthe quill.-

Other objects and advantages ofthe invention wi1l:appear from the following description taken in connection with the drawings. in which-:-

Fig. 1 is a small scale. side elevation showing one type of milling machine towhich this invention is applicable.

Fig. 2 is a fragmentary' plani section take a substantially as indicated at line 2-2 on. Fig-l 1 and on Fig. 4.

Fig, 3 is a fragmentary front elevation taken substantially as indicated atline: 3P4 on Fig.2..

Fig. 4 is a fragmentary side. elevation with a.

portion of the frame or housing. broken away'anct showing the stop members therein insectiona.

Figs. 5, 6 and 7 are diagrams representing. varieous work cycles in which the shifting. of the quilland consequent shiftingv of the-cutter are feae tures of thecycle of operation While there is shown in. thedrawings and-de:-. scribed in detail herein certain structure embodywhile the drive pinion 22 and its motor 23 are ing this invention, it is to be understood that the same is not limited to the specific form or application disclosed and that it is the intention to cover all modifications and alternative constructions falling within the scope of the in-' vention as expressed in the claims.

The milling machine illustrated in Fig. 1 is ofthetype having an upstanding frame II] with a horizontally movable work table II and a cutter 10. [2 which rotates upon a horizontal axis. The

cutter shaft or spindle is journaled in a sleeve or quill is which is slidably mounted in the frame I0 so that it can be adjusted axially within a limited range for shifting the position of the cutter l2 in carrying it to the work or retracting it therefrom. Since the accuracy of the work performed by the cutter depends uponhaving the cutter held rigidly in a definite position durin its operation, it is important that the adjustmentof the quill be accomplished in a manner which insures its definite positioning at its limits ofmovement', and, particularly, at the working limit, The present invention is concerned with means for moving the cutter between its limits,-

means for determining the limits of movement accurately, and means for holding the cutter at such limits during operation of the machine.

As shown in Fig. 2, the quill I3 is provided with a rack l4 and is guided for reciprocation in the frame In of the machine. A driving pinion l5 meshes with the rack I4 for effecting axial movement of the. quill, and this pinion l5 meshes with a gear l6 which in turn meshes with a rack l! on a rod l8 which is shown mounted for reciprocation in a direction transverse to the axis of the quill 13. A portion of the rod I8 is threaded at I9; .and this threaded portion is engaged in a threaded sleeve or nut 20 which. carries a gear 2| meshing with the drive pinion 22 of a motor The nut 20. and gear 2| appear in Fig. 2,

clearly shown in Fi 3. It will be evident that upon rotation of the motor 23 the pinion 22 turns the gear 2| and with it the nut 20, and that this rotation of the. nut 20 produces longitudinal movement of the rod l8 threaded in the nut 28 and held against rotation by the engagement of a key member 24 with a key way IBa cut in.

one side of the rod l8. Longitudinalmovement of therod l8 causes its rack teeth I! to rotate the gear 16 and pinion l5, thus driving the rack l4 and the quill l3 onwhich it is formed or se cured.

Just below the pinion I5 there is a pinion 25 journaled Zoaxially with the pinion l5 and on the 3 same shaft 26 but rotatable independently of the pinion 15. The pinion 25 also meshes with the rack l4 and is driven thereby in one direction or the other whenever the quill I3 is shifted. The pinion 25 meshes with a rack 21 on a rod 28 shown mounted for reciprocation in a direction parallel to the axis of the quill l3. One end of the rod 28 enters a special housing 29 inside the main frame of the machine, this housing serving to support adjustable stop members 30 and 3|.

The end surface 30a of the stop member 30 operates with the end surface 28a of the rod 28 to limit movement of the rod in one direction.

The stop member 3| has a portion cutaway at a cooperating stop face 282) to limit movement of the rod in the other direction.

The stop members 38 and 3! are slidable in guide bores 32 and 33 respectively, which are formed in the housing 29, and the stop members, being cylindrical, are held against rotation by set screws 32 having reduced end portions engaged in longitudinal grooves 390 and 310 in the stop members respectively. The member 36 is internally threaded at one end and is engaged with an adjusting screw 35, while the member 3| is similarly threaded and engaged with an adjusting screw 36. Both screws are provided with squared terminals 35a and 35a respectively, so that a suitable handle or wrench may be applied for operating them. It will be evident that by longitudinal adjustment of the stop members 33 andsl, by means 01'' their adjusting screws 35 and 3B, the distance between the stop shoulders or faces 32a and Slb may be varied and the particular positions of these faces may be shifted so as to vary the range of movement of the quill and the position at which that movement shall take place in respect to the work table of the machine. I

As the quill travels outwardly under the driving force imparted to it through the gear l5 and pinion [5, the pinion 25 will transmit an equal and oppositemovement to the rod 28 which will continue to travel until it strikes the stop shoulder 30a. The driving effort transmitted from the quill through the pinion 25 and rack 27 will have taken up all backlash in this connection so that the quill will be positively arrested the instant the surface 28a of the rod 28 engages the stop.

surface 3611. Any backlash in the drive connection between the motor 23 and the rack M of the quill will have been taken up in the driving effort imparted to the quill; hence, there will be no opportunity for further rotation of the motor after the stop 38a is encountered. However, this motor is preferably of the reversible torque type designed to remain in circuit under this condition and to impart a continuous torque to the driving train for holding the parts rigidly at the limit determined by the position of the stop member 30.

It may be understood that the working cycle of the machine and the operation of the milling Thereupon the pinion 22 will drive the gear 2! and the remainder of the connecting train, including the pinion l5 and rack it, so as to'move the quill inwardly with respect to the frame of- 4 the machine. Simultaneously, the pinion 25 will transmit movement to the rod 28 for shifting it in the opposite direction and with the backlash taken up between the rack I4, pinion 25 and rack 27, the rod 28 will continue to move until the stop face 281) strikes the stop shoulder MD of the stop member 3!. Thereupon the parts will come to rest instantly with the torque motor remaining in circuit to hold the stop face 28b against the stop shoulder Bib and retain the quill i3 rigidly at this limit of its movement.

Fig. 5 illustrates one class of Work which utilizes the axial adjustment of the quill and represents diagrammaticallythe cycle of movement for operation on the work. In this case, the work is shown as a piece having a. deep recess 40. The surface 4! tobe faced is located within this recess. Accordingly, while the work is being set up on the work table, the cutter must be retracted to a position such as that indicated at a. Then, as the machine is started, the advance of the quill carries the cutter I2 horizontally along the a line ab into position for operation on the surface M The feed of the Work table then effects relative horizontal movement of the cutter across the surface 4| along the line he. Upon completion of the facing operation, the quill'then retracts the cutter horizontally alongthe line ed and thereafter a rapid return movement of the work table brings the relative position of the cutter back to a. t

Fig. 6 illustrates another typical-work cycle'in which the movement of the quill plays a part.

tool will usually be controlled automatically by In this case the work piece has an external surface 42 to be faced. Starting at the point e'the. diagram indicates that the cutter l2 'is'shifted by movement of the quill from c to J at which it.

is in the plane in which it will operate to machine the surface :22. Movement of the work table then effects relative movement of the cutter from f to g for the machining operation. At g the work table is arrested and the quill withdraws the'cut-' ter from g to h. Thereafter, the rapidreturn movement of the work table effects relative movement of the cutter from h to e.

In the cycle illustrated diagrammatically. in Fig. 7, it is assumed that the surface liiof the work piece is to be given a roughing cut and a finish cut. The initial position of the cutter I2 is indicated at 7' at some distance from the work piece toafiord space for setting up the workon the work table of the milling machine: When this has been accomplished and the machine started the table first eifects a rapid approach which brings the relative. position of the cutter from 9' to 7c.. Thereafter, the table feed continues at cutting speed, while the. cutter accomplishes a roughing cut from k to Z. At 1 the work table is arrested and the quill moves. toward the work by a slight distance corresponding to the depth of the finish cut to be made. Then upon reverse travel of the work table the'finish cut is accomplished by the cutter in its relative movement from m to n. Thereafter, the work table is speed ed up for rapid return and the relativeposition of the cutter is shifted from n to 0. Then; the

movement of the quill returns the cutter toits initial position at a.

As already statedthe timing of the various I table movements and of the' shifting ofth'e-quill may be accomplished. by a suitable program mechanism, and the planned cycle will then be accurately carried out by virtue" of the positive control ofthe quill movement afforded-by the mechanismwhich is the subject of this invention.

amuse It may 'be understood tha-tthe mechanism for controlling the quill in accordance with this in vention is applicable to a quill and spindle mounted for vertical adjustment as well as to the'horizontall-y disposed quill illustrated herein and that change. In fact, Figs. 5, 6 and '7 would illustratesuch cycles with the understanding that the initial movement of the cutter in each case as it is fed into position for work is in-a vertical direction.

I claim as my invention:

1. In a milling machine which includes a trance and a quill slidably mounted therein, means for shifting said quill comprising a rack on the quill, a first pinion meshing with said rack, a motor and; drive gearing connecting said motor with the pinion, a second pinion independent of said first pinion and also meshing with the rack on the quill, a slidably mounted rod having a rack in mesh with the second pinion, said rod having a pair of oppositely facing stop shoulders, and a pair of stops engageable by saidshoulders respective- 13! for limiting the travel or the quill.

2. In a milling machine which includes a frame and a quill slidably mounted therein, means for shifting said quill comprising a first member drivingly engaging the quill, a motor and drive gearing connecting said motor with said first member, and means for limiting a slidable range of the quill comprising a slidably mounted rod having a pair of oppositely facing stop shoulders, drive gearing independent of said first member and including a second member in engagement with and driven by said quill, said independent drive gearing being arranged to transmit motion from the quill to the rod in either direction, and a pair of stops engageable by said shoulders respectively for limiting the travel of the quill.

3. In a milling machine which includes a frame and a quill slidably mounted therein, means for shifting said quill including a motor and drive gearing connecting said motor to the quill, a slidably mounted rod having a pair of oppositely vfacing stop shoulders, a rack on the quill, a pinion independent of said drive gearing meshing with said rack and arranged to transmit motion from the quill to the rod together with a pair of stops engageable by said stop shoulders on the rod re spectively for limiting the travel of the quill.

4. In a milling machine which includes a frameand a quill slidably mounted therein, means for shifting said quill including a gear, a slidable member having rack teeth meshed with said gear, a portion of said member being threaded, a nut on said threaded portion mounted for rotation and held against axial movement, a motor and gearing connecting said motor to the nut for rotating it, together with means operatively connecting said gear to the quill, a sli-dably mounted rod having a pair of oppositely facing stop shoulders, drive gearing which is independent of said first mentioned gearing and is arranged to transmit motion from the quill to the rod in either direction and a pair of stops engageable by said shoulders respectively for limiting the travel of the quill.

5. In a milling machine which includes a frame and a quill slidably mounted therein, means for shifting said quill including a gear, a slidable member having rack teeth meshed with said gear, a portion of said member being threaded, a nut on said threaded portion, bearings in which the nut is held against axial movement, a motor and gearing connecting said motor to the nut for rotating it; together: with-means operativelydon-'5 necting-said gear to the quill, a rack. on the quill, a pinionmeshingwith said rack, a-sli-dablymount edrod having a rack-in mesh with said pinion, said rod having a stop shoulder and a fixed) stop engageable by said shoulder for limiting traveled? the quilt, saidmotor being a torque mo--- tor adapted to remain in circuit for holding the quill at-the limlt ofitsi'lra'v'el.'= i

G, In a mil-ling inachine which includes a frame and a quill slidably= mounted: therein;- meansforshifting said quill comprisinga rack on the quill, a pinion meshing with-said racli'," a motor and drive gearing connecting saidmotor. with the pinion-including a slidable memberihaving a rack and-'having-al'so a threaded portion and anut on the threaded portion held against endwise move mentbutrotatable by said motor, a second pin ion also I meshing With the rack: on the quills a reciprocably mounted rod having a rack in mesh with the-second pinion,- said r-o'd having aapair of oppositely dacirig stop shoulders, and'a pair oiaddustable stops engageable' by said: shoulders respectively for'determini-ng the limits of traveli oi thequill. l

7. In a milli-r-rg machine which includes a frameand a quill slidably mounted therein, means for shifting said quill comprising a rack on the quill, a pinion meshing with said rack, a gear meshing with the pinion, a slidable member having a rack meshing with said gear and having also a threaded portion, a rotatable nut on the threaded portion held against axial movement, a gear operatively associated with the nut and a motor having a drive pinion meshing with said gear, a second pinion journaled coaxially with the first but unconnected therewith and also meshing with the rack on the quill, a rod mounted for reciprocation parallel to the quill and having a rack in mesh with the second pinion, said rod having a pair of oppositely facing stop shoulders, and a pair of adjustable stops mounted in the frame engageable by said shoulders respectively for determining the limits of travel of the quill, said motor being a reversible torque motor adapted to remain in circuit for holding the quill at either limit of its travel.

8. In a milling machine which includes a frame and a quill slidably mounted therein, means for shifting said quill comprising a rack on the quill, a first pinion meshing with said rack, a motor and drive gearing connecting said motor with the pinion, a second pinion independent of said first pinion and also meshing with the rack on the quill, a slidably mounted rod having a rack in mesh with the second pinion, said rod having a pair of stops supported by the frame laterally adjacent said rod each stop comprising a part rotatably mounted in the frame but fixed against axial movement, and a part slidable in the frame with means preventing its rotation about its axis, said parts being coaxially disposed and being threaded together whereby rotation of one part adjusts the other part longitudinally for varying the position at which it will engage the stop shoulder of the rod.

9. In a machine tool which includes a frame, a work support and a tool support mounted in the frame for sliding movement therein relative to the work support, means for shifting said tool support comprising a driving member engaging said tool support, a motor and drive gearing connecting said motor to said driving member, and means for limiting the sliding movement of the tool support comprising a slldably mounted memher having'a pair of oppositely facing stop shoulders, drive gearing independent of said first mentioned drive gearing and including a driven memher also in engagement with said tool support, said independent drive gearing being arranged to transmit motion from the tool support to said slidably mounted member in either direction, and a pair of stops engageable by said shoulders respectively for limiting. the travel of the tool support, said motor being a reversible torque motor adapted to remain in circuit for holding the tool support at either limit of its travel. 7

10. In a milling machine which includes a frame and a quill slidably mounted therein, means for shifting said quillcomprising a first member drivingly engaging said quill, a motor and drive gearing connecting said motor with said memher, and means for limiting the slidable range of the quill comprising a slid-ably mounted member having a stop shoulder, drive gearing independent of said first mentioned drive gearing and including a second member also in engagement with said quill, said independent drive gearing being arranged to transmit motion from the quill to said slidably mounted member, and positive stop means engageable by said stop shoulder for accurately arresting the quill at one limit of its travel. I 1

8 11. In a milling machine which includes ai'rame and a quill sli-dably mounted therein, means for shifting said quill comprising a first member engaging the quill, a torque motor and drive gearing connecting said motor with said member, movable abutment means which derives its movement from the quill independently of said drive gearing, drive means for said movable abutment means, such drive means including a second memher also in engagementwith the quill, and fixed stop means positively engaging said movable abutment means and arresting the quill accurate- 1y at one limit of its travel.

CARL) LELAND HOLMSTROM.

REFERENCES CITED The following references are of record in the file of this patentzr UNITED STATES PATENTS 

